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Polycythemia and Hyperviscosity in the Newborn

Red blood cells carry oxygen in the blood. Polycythemia occurs when a baby’s blood has more red cells than normal. (It’s the opposite of anemia, which is caused by too few red cells.) The extra red cells make the blood thicker. When blood is too thick, it travels through the body more slowly than normal. This problem is called hyperviscosity. As a result, some organs may not get enough oxygen.

What Causes Polycythemia?

The problem may be caused by one of the following:

The baby’s body is making more red blood cells than it should.

The baby received extra red blood cells from another source (such as from a twin during pregnancy).

Just after birth, too many red blood cells traveled from the umbilical cord to the baby before the cord was clamped.

How Is Polycythemia Detected?

A baby with polycythemia has skin that looks red, especially while the baby is crying. This is often the first sign of a problem. A blood test (called a hematocrit) is then done to measure the level of red blood cells. If the number is too high, treatment may be needed.

How Is Polycythemia Treated?

Treatment will depend on the level of red blood cells (hematocrit), as well as the presence or absence of symptoms.

Treatment in more severe cases may involve removing some of the baby's blood and replacing it with fluid through an IV line. This dilutes (waters down) the blood, so red blood cells are less concentrated. This treatment is called a partial exchange transfusion.

What Are the Long-Term Effects?

In most cases, polycythemia has no lasting effects. As the extra red blood cells break down, the baby will probably have jaundice (yellowing of the skin) for a short time. This is normal. If a blood clot (thrombus) or other problems occurred due to hyperviscosity, the baby may have complications such as stroke or organ damage. Talk to the doctor about how your baby is likely to progress.